MONTPELIER — A coalition of 32 environmental groups, businesses and other organizations are calling for improved protection of Vermont’s rivers and lakes, including Lake Champlain and the Connecticut River.

Among the biggest threats seen by the groups is an overload of nutrients, including phosphorus flowing into the state’s rivers from both farms and yards. The groups say incidents like algae blooms in Lake Champlain’s Missisquoi Bay harm the state’s tourism economy.

Lori Fisher of the Lake Champlain Committee says the state’s public water supply infrastructure alone needs nearly $400 million in upgrades in the next 20 years.

Chris Kilian of the Conservation Law Foundation says the state needs to focus on tougher enforcement of its environmental laws.